Hose couplings are used in a wide variety of applications for connecting a flexible hose to a metal tube. One such application is in automobile power steering circuits, wherein the flexible hose is coupled to one end of a metal tube, and the other end of the metal tube is connected to the power steering pump or to the power steering valve. In such applications for hose couplings, it is necessary that the coupling withstand adverse conditions of temperature variations, pressures pulsations, and engine vibrations.
A widely used prior art hose coupling and method are illustrated in FIG. 3 of the drawings. The flexible hose is inserted into an annular cavity between a collar and the metal tube, and the collar is then crimped radially inwardly to squeeze the hose between the collar and the metal tube. A reinforcing sleeve is placed inside the metal tube so that the crimping of the collar does not collapse the metal tube.
Although this prior art coupling and method illustrated in FIG. 3 have enjoyed wide commercial acceptance, they provide a relatively complex solution to the problem of coupling a hose to a metal tube. In order that the tube coupling not restrict the flow of fluid, the metal tube is expanded at its free end so that a reinforcing sleeve having an inner diameter approximately equal to the normal inner diameter of the metal tube can be inserted into the metal tube. After expansion of the metal tube, a rear bead is formed on the tube by axial bumping of the free end of the tube. A collar is then placed on the expanded free end of the tube, and a front bead is formed on the tube to secure the collar in place.
Other prior art couplings are shown in U.S. Pat. Nos. 3,345,091 and 3,787,945.